<a mat-raised-button (click)="favor()" *ngIf="!isFavor">
    <i class="fa fa-heart-o" aria-hidden="true"></i>收藏
</a>
<a mat-raised-button (click)="unfavor()" *ngIf="isFavor">
    <i class="fa fa-heart" aria-hidden="true"></i>取消收藏
</a>